Investigations
1st investigations to order
Schirmer's test
anti-60 kD (SS-A) Ro and anti-La (SS-B)
Test
Antibodies to the ribonucleoproteins 60 kD Ro and La are found in up to 90% of patients with Sjogren syndrome.[22]
Anti-60 kD Ro is not specific to Sjogren syndrome and is found in other auto-immune disorders, particularly lupus.[21]
Studies suggest that the level of anti-60 kD Ro and anti-La in the patients is correlated with earlier disease onset, longer disease duration, recurrent parotid gland enlargement, and extraglandular manifestations.[22]
Vasculitis is associated with the presence of anti-Ro and anti-La in the sera of patients with SS.
Result
positive
Investigations to consider
sialometry
Test
Measures unstimulated salivary flow for 15 minutes into a calibrated tube. Does not differentiate between causes of xerostomia.[77]
Result
decreased
minor salivary gland biopsy
Test
Mononuclear cell infiltrates (B and T cells and dendritic cells) in perivascular or periductal areas of sampled gland. Focus score of 1 is defined as the number of mononuclear cell infiltrates containing at least 50 inflammatory cells in a 4 mm² glandular section.[79]
A focus score of 1 or greater is supportive of the diagnosis of Sjogren syndrome and satisfies the American-European criteria in the presence of dry eye or dry mouth symptoms, and objective evidence of keratoconjunctivitis sicca or salivary hypofunction.[69]
Result
focus score 1 or greater
lissamine green test
Test
In the lissamine green Ocular Staining Score (OSS), grade 0 is defined as 0 to 9 dots of lissamine green staining of the interpalpebral bulbar conjunctiva (nasal and temporal bulbar conjunctivae graded separately); grade 1 is defined by the presence of 10 to 32 dots; grade 2 is defined by the presence of 33 to 100 dots; and grade 3 is defined by the presence of more than 100 dots.[80]
An OSS higher than 0 is considered to be abnormal and may be a sign of keratoconjunctivitis sicca, but scores of 1 or 2 can also represent a late staining artefact if interpretation of the fluorescein corneal staining pattern is delayed beyond 8 minutes. (Examination and grading of the eyes should be performed immediately after instilling lissamine green dye because the intensity and extent of the ocular staining diminishes rapidly after the first 2 minutes.) As this could lead to a high level of misclassification, an abnormal OSS is defined as being a score of 3 or more.[80]
Rose bengal staining has been largely supplanted by lissamine green staining, because the former is very painful to patients with keratoconjunctivitis sicca.
Result
score of 3 or more
fluorescein corneal staining test
Test
To elucidate corneal abrasion and ulcer.
Result
score of 3 or more
parotid sialography
salivary gland technetium-99m pertechnetate scintigraphy
skin biopsy
Test
Skin biopsy enables diagnosis of vasculitis in Sjogren syndrome patients with skin rash.
Result
focal and segmental transmural necrotising inflammation in a medium-sized vessel (i.e., a small or medium-sized artery)
angiography
Test
Useful in Sjogren syndrome patients with vasculitis with large vessel involvement.
Result
beading, aneurysm, or smooth, tapering vessel stenosis
urinalysis
Test
In Sjogren syndrome patients with suspected renal tubular acidosis.
Result
may show abnormal levels of phosphate, calcium, potassium, glucose
serum electrolytes
Test
In patients with suspected renal tubular acidosis.
Result
may show hypokalaemia with a normal anion gap; hyperchloraemic metabolic acidosis
Emerging tests
MRI salivary glands
Test
Investigational, best performed in research centres.
Result
inflammation of salivary glands
ultrasound salivary glands
Test
Correlations between salivary gland ultrasound results and focus score in the major salivary glands have been shown.[71][72][73] A subsequent study demonstrated that two four-grade semi-quantitative salivary gland ultrasound (SGUS) scoring systems (Outcome Measures in Rheumatology [OMERACT] and De Vita et al) are reliable for the evaluation of salivary glands in patients with primary Sjogren syndrome.[74]
Result
high salivary gland ultrasonography score
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